In the assembly of electronic devices, integrated circuit chips are often enclosed in a package having a plurality of terminals for connection to the outside world. The industry seems to be trending toward an ever increasing number of such terminals while the packages are being kept as small as possible to conserve space in service. Consequently, external terminals are becoming more densely arranged and adapting them for connection has become a significant problem.
In a typical chip carrier, the terminals are arranged in four rows extending along four edges of a square surface. The terminals are usually flat metal pads which are later bonded to a corresponding array of terminal pads or flat leads on a ceramic or Printed Circuit (P-C) board. To prepare for such bonding, it is customary to fuse a preformed body of bonding material to each terminal of a carrier. Later, when the carrier is to be bonded to the board, the array of such bodies of material are simultaneously heated and reflowed to form conductive connections between carrier terminals and board terminals.
Heretofore, preformed bodies of bonding material have been manipulated by various expedients depending upon their size and shape and the number to be applied in a given cycle. For I.C. chip carriers, tiny spheres are selected for economy, and arrays of 20-48 spheres have been simultaneously applied in the past, often engaged by an array of vacuum cups. A problem is that the cups do not readily retain spheres which may be irregular in shape and vacuum tends to draw flux from the bonding sites.
Consequently, it is desirable to provide new and improved expedients for applying bodies containing bonding material. It is also desirable to engage individual bodies which may be irregular in shape and to apply them to bonding sites without disturbing flux thereon. More particularly, it is advantageous to substantially simultaneously apply ones of bodies containing bonding material to each of an array of bonding sites.